6分钟让你精通双向链表：从零到精通JavaScript实现

2023-10-25 11:39:44

双向链表入门

在计算机科学中，双向链表是一种存储元素并允许按顺序访问它的数据结构。每个元素都包含一个值和两个指针，分别指向链表中的前一个和后一个元素。

JavaScript实现

创建双向链表

class Node {
  constructor(value) {
    this.value = value;
    this.next = null;
    this.prev = null;
  }
}

class DoublyLinkedList {
  constructor() {
    this.head = null;
    this.tail = null;
    this.length = 0;
  }
}

增添元素

append(value) {
  const newNode = new Node(value);
  if (this.length === 0) {
    this.head = newNode;
    this.tail = newNode;
  } else {
    this.tail.next = newNode;
    newNode.prev = this.tail;
    this.tail = newNode;
  }
  this.length++;
  return this;
}

prepend(value) {
  const newNode = new Node(value);
  if (this.length === 0) {
    this.head = newNode;
    this.tail = newNode;
  } else {
    newNode.next = this.head;
    this.head.prev = newNode;
    this.head = newNode;
  }
  this.length++;
  return this;
}

insert(position, value) {
  if (position < 0 || position > this.length) {
    throw new Error("Invalid position");
  }
  if (position === 0) {
    return this.prepend(value);
  }
  if (position === this.length) {
    return this.append(value);
  }

  const newNode = new Node(value);
  const prevNode = this.getNodeAt(position - 1);
  const nextNode = prevNode.next;

  prevNode.next = newNode;
  newNode.prev = prevNode;
  newNode.next = nextNode;
  nextNode.prev = newNode;

  this.length++;
  return this;
}

删除元素

removeAt(position) {
  if (position < 0 || position >= this.length) {
    throw new Error("Invalid position");
  }
  if (position === 0) {
    return this.removeHead();
  }
  if (position === this.length - 1) {
    return this.removeTail();
  }

  const prevNode = this.getNodeAt(position - 1);
  const nodeToRemove = prevNode.next;
  const nextNode = nodeToRemove.next;

  prevNode.next = nextNode;
  nextNode.prev = prevNode;

  this.length--;
  return nodeToRemove;
}

其他方法

find(value) {
  let currentNode = this.head;
  while (currentNode !== null) {
    if (currentNode.value === value) {
      return currentNode;
    }
    currentNode = currentNode.next;
  }
  return null;
}

reverse() {
  let currentNode = this.tail;
  this.head = currentNode;
  this.tail = this.head.prev;

  while (currentNode !== null) {
    const nextNode = currentNode.prev;
    currentNode.prev = currentNode.next;
    currentNode.next = nextNode;

    currentNode = nextNode;
  }
}